Have you changed settings in the bios of your PC Gamer and it refuses to start? Have you tried Overclocking which made your system unstable? Do you see error LEDs lighting up on your motherboard? You may need to do a Clear CMOS! Clear CMOS is an operation that resets the BIOS settings, the software that manages the basic components of your computer. In this article, we will explain to you what Clear CMOS is and how to perform it safely.
Clear CMOS and BIOS: what is the relationship?
BIOS ( Basic Input Output System ) is software that allows you to configure the basic settings of your computer, such as boot order, processor frequency, memory voltage, etc. The BIOS is stored on a memory chip called CMOS ( Complementary Metal Oxide Semiconductor ), which is powered by a small battery on the motherboard.
Sometimes it can happen that the BIOS freezes or becomes unstable due to mishandling, failed overclocking, failed update or virus. In this case, it may be necessary to reset the BIOS to factory settings, which is called doing a Clear CMOS.
Clear CMOS involves cutting off the power supply to the CMOS chip for a few seconds, which erases the data it contains and resets the BIOS. There are several methods for making Clear CMOS, which we will explain to you in this article.
How to reset your PC's BIOS using Clear CMOS?
Method 1: Use the Clear CMOS button
Some motherboards have a dedicated button to do Clear CMOS . It's usually on the back of the case, near the USB or audio ports. If your motherboard has one, here's how to do it:
- Turn off your computer and unplug the power supply cable or turn the power supply switch OFF.
- Press the Clear CMOS button for 5-10 seconds.
- Reconnect the power supply cable or turn the power supply switch back to ON.
- Turn your computer back on and enter BIOS to verify that the settings are reset.
Method 2: Use Clear CMOS Jumper
If your motherboard does not have a Clear CMOS button, you can use a jumper to do the same operation. A jumper is a small metal connector that connects two pins on the motherboard. You need to find the two pins dedicated to Clear CMOS, which are usually indicated by the letters CLR, CLRCMOS, CLRTC or JBAT. You can consult your motherboard manual to locate them. Here's how to do it:
- Turn off your computer and unplug the power supply cable or turn the power supply switch OFF.
- Open your computer case and locate the two Clear CMOS pins on the motherboard.
- Place the jumper on both pins for 5-10 seconds, then remove it. If you don't have a jumper, you can use a screwdriver or paperclip to make contact between the two pins.
- Reconnect the power supply cable or turn the power supply switch back to ON.
- Turn your computer back on and enter BIOS to verify that the settings are reset.
Method 3: Remove the CMOS Battery
If you cannot find the Clear CMOS button or pins, you can remove the battery that powers the CMOS chip. This is a round CR2032 type battery, which is usually found near the processor or memory on the motherboard. Here's how to do it:
- Turn off your computer and unplug the power supply cable or turn the power supply switch OFF.
- Open your computer case and locate the CMOS battery on the motherboard.
- Remove the battery from its location, being careful not to damage the contacts. You can use a small flathead screwdriver to dislodge it.
- Wait 5 to 10 seconds, then replace the battery.
- Reconnect the power supply cable or turn the power supply switch back to ON.
- Turn your computer back on and enter BIOS to verify that the settings are reset.
FAQs
What are the risks of Clear CMOS?
Clear CMOS is a safe operation for your computer, provided you respect the following precautions:
- Turn off and unplug your computer before handling the motherboard.
- Avoid touching electronic components with fingers or metal objects.
- Return the button, jumper or battery to their original position after Clear CMOS.
Clear CMOS is a safe operation for your computer, provided you respect the following precautions:
- Turn off and unplug your computer before handling the motherboard.
- Avoid touching electronic components with fingers or metal objects.
- Return the button, jumper or battery to their original position after Clear CMOS.
The only downside to Clear CMOS is that you will lose any custom settings you made in the BIOS. It is therefore advisable to note your settings before doing a Clear CMOS, or to create a profile in the BIOS to save them.
When to make a Clear CMOS?
Clear CMOS is useful in the following situations:
- Your computer does not start or freezes after changing settings in the BIOS, for example to overclock your processor or memory.
- Your computer displays error messages during startup, such as “CMOS checksum error” or “CMOS battery failure.”
- Your computer has been infected with a virus that has corrupted the BIOS.
- Your computer is stuck on the “Diagnosing your computer” error message and you cannot access the operating system.
- You want to reset the BIOS to factory default settings.
How to enter BIOS?
The BIOS is accessible when your computer starts up, by pressing a specific key. This key varies by brand and model, but is usually F1, F2, F10, F12, Del, or Esc. You must press the key when your computer manufacturer's logo appears on the screen. If you miss the right moment, you can restart your computer and try again.
How to update BIOS?
The BIOS may be updated to fix bugs, improve compatibility, or add features. To update the BIOS, you need to download the latest version of the software from your motherboard manufacturer's website, then install it from the BIOS or from Windows . Be careful, this is a delicate operation which can render your computer unusable in the event of an error or power outage. It is therefore recommended to carefully follow the manufacturer's instructions and not interrupt the update process.
What is the difference between BIOS and UEFI?
The BIOS is the historical software that allows you to configure the basic settings of your computer. UEFI (Unified Extensible Firmware Interface) is newer software that is gradually replacing the BIOS. UEFI offers more features than BIOS, such as a GUI, better security, faster booting, or support for hard drives larger than 2TB. If your computer is new, it probably uses UEFI instead of BIOS. The term BIOS is, however, often misused to designate UEFI.
Conclusion
Clear CMOS is an operation that resets the BIOS to factory settings. There are several methods to make a Clear CMOS, such as using a button, a jumper or removing the CMOS battery. Clear CMOS is useful in case of startup problems or instability of your computer after changing settings in the BIOS, for example to overclock your processor or memory. Clear CMOS allows you to reset the BIOS and resolve any conflicts or errors.
We hope this article was helpful to you in understanding what Clear CMOS is and how to perform it. If you have any questions or comments, please feel free to leave them below.
